Japanese Beetles

Japanese Beetles

Description:

The Japanese beetle, Popillia japonica Newman, is a widespread and destructive pest of turf, landscape, and ornamental plants in the United States. It is also a pest of several fruit, garden, and field crops, and has a total host range of more than 300 plant species. Adult Japanese beetles feed on foliage, flowers, and fruits. Leaves are typically skeletonized or left with only tough network of veins.

The larvae, commonly known as white grubs, primarily feed on roots of grasses often destroying turf in lawns, parks, and golf courses. Currently the Japanese beetle is the most widespread pest of turfgrass and costs the turf and ornamental industry approximately $450 million each year in management alone (Potter and Held 2002).

Hosts:

Larvae feed on roots of turf grasses as well as those of other plants. Adults feed on more than 300 different plant species and are considered major pests of ornamental, fruit, and vegetable plants. Japanese beetles are especially fond of flowering crabapple, roses, and grapes, so it is best to avoid planting these highly susceptible host plants. Also avoid planting Japanese maple (Acer palmatum), Rose‐of‐Sharon (Hibiscus syriacus), flowering cherry (Prunus spp.), and American elm (Ulmus americanum) as these are also favored by adult beetles. However, some varieties of certain host plants such as roses are less susceptible than others.

Damage:

Adults feed during the day, preferring hot weather and plants located in full sun. Damage to foliage appears as skeletonized tissue with all but the leaf veins entirely consumed. Adult feeding activity on fruits and flowers typically is characterized by holes in affected tissue; large numbers of beetles will often consume these plant tissues in their entirety. Healthy plants can survive even complete defoliation by the beetle, but young or weak host plants may not be able to withstand heavy attacks. In fruit and vegetable crops,
yield may be reduced as a result of defoliation.

Cultural control:

Handpicking adult beetles can be effective when they first colonize landscape plants. Beetles are less active in the morning and evening when it is cooler and can be killed by dropping them in a solution of soapy water. Japanese beetle traps, which contain a sex pheromone and a floral lure to attract both males and females, have been commercially available for several years. However, these traps usually attract more beetles than they capture, leaving landscape plants vulnerable.

Adult Japanese beetles can fly one mile or more, so beetles that are caught in traps are readily replaced in the landscape by colonizing individuals. The only situation where traps may be useful is if traps are used across a large area JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC. Life cycle of Japanese beetle. Traps should be checked and emptied regularly, but make sure to kill any live beetles by dunking them in soapy water.

Chemical control:

There are many insecticides labeled for Japanese beetle control, and several are available to homeowners. Look for insecticide products containing acephate (Orthene), carbaryl (Sevin), bifenthrin, cyfluthrin, deltamethrin, lambda‐cyhalothrin, or permethrin. Applications of imidacloprid (e.g., Bayer Advanced Tree & Shrub Concentrate) should be made at least 20 days prior to Japanese beetle adult activity. When adult activity is heavy, insecticide sprays may be needed every 5 to 10 days. In general, soil applications of insecticides to target larvae will not reduce adult Japanese beetle populations because they colonize from
surrounding areas.